Kubernetes do I need to include port when directing? - nginx

Question

I have an application running in K8s. It has 3 microservices and nginx in front of them.
Each redirection goes through nginx first and is proxied as specified.
My flask app is having issues redirecting without the port number. I run k8s locally via minikube. Whenever I redirect to another page the url doesn't include port number, which throws me an error.
if usernamedata == None:
print("Could not log in")
else:
if passworddata == password:
print("Logged in")
return redirect("/user/{0}".format(username))
Nginx is the only service exposed and its url is
http://192.168.99.107:31699
With my redirection in flask I get redirected to http://192.168.99.107/user/David, which throws me connection refused.
If I add port number and make it http://192.168.99.107:31699/user/David it works fine.
Do I need to specify port number when redirecting? What if the service is down and recreated?
Also, this is my service definition for nginx:
kind: Service
apiVersion: v1
metadata:
name: nginx
labels:
svc: nginx
spec:
selector:
app: nginx-app
type: LoadBalancer
ports:
- port: 80
How can I make redirection within flask app work?

Answer 1

If service is down and recreated and you want to retain same high port number for your service you need to specify nodePort and change type of service to NodePort.
apiVersion: v1
kind: Service
metadata:
name: my-service
labels:
svc: nginx
spec:
type: NodePort # type is set to NodePort
ports:
- port: 80 # Service's internal cluster IP
targetPort: 80 # target port of the backing pods
nodePort: 31699 # service will be only available via this port for each cluster node if recreated
selector:
app: nginx-app
Within your Python code (If Service starts before Pod):
import os
...
service_host = os.environ.get("NGINX_SERVICE_HOST")
service_port = os.environ.get("NGINX_SERVICE_PORT")
...
redirect(f"http://{service_host}:{service_port}/user/{username}")